3 Pendulum Harmonograph

My combination three-pendulum harmonograph and coffee table

What the heck is a harmonograph?

As a portion of my design technologies class, I decided to construct a 3-pendulum harmonograph akin to the one found here. Using many of the same base ideas I went through each component in AutoCAD 2010, producing a detailed build-log along the way.

The table with the coffee table conversion complete

A helpful video showcasing my harmonograph

About my Harmonograph:

When I was looking into the feasibility of constructing a harmonograph, one of my concerns was the size of the device. The harmonograph table is 3' by 3' and has a table surface that is high above the ground. To make the harmonograph more useful to me in the long-term I decided to construct the project as harmonograph first and as a coffee-table second. This means that by removing 8 bolts and unscrewing two more from the drawing arm-pendulum connection, the table can be converted for use as a coffee table, with covers for the holes in its surface.

"A harmonograph is a mechanical apparatus that employs pendulums to create a geometric image. The drawings created typically are Lissajous curves, or related drawings of greater complexity. The devices, which began to appear in the mid-19th century and peaked in popularity in the 1890s, cannot be conclusively attributed to a single person, although Hugh Blackburn, a professor of mathematics at the University of Glasgow, is commonly believed to be the official inventor."

Pictures:

These are some images of the progression, I regret not taking more pictures of the table in earlier stages.

Gluing on the table surface, using heavy things to hold it in place,

Some initial testing with much less weight than needed and the results.

The completed harmonograph with correct weights installed.

The first Lissajous curve with my new harmonograph! I used the table with the 9 x 2.5lb weights affixed.

Some more Lissajous curves created with mostly 1:1 weight and frequency ratios